Hydraulic transmitter mechanism



Aug. 19, 1952 E. M. MAY

Filed Dec. 30, 1946 4 Sheet-Sheet 1 INVENTOR.

' ATTORNEY E. M. MAY

HYDRAULIC TRANSMITTER MECHANISM Aug. 19, 1952 4 Sheets-Sheet 2 Filed Dec. 30, 1946 n Q m 2Q km g Z W W a W m E5 Ykkw1ihflW m m R Ely w m I III I T u QN A Aug. 19, 1952 E. M. MAY 2,607,196

HYDRAULIC TRANSMITTER MECHANISM Filed Dec. 30, 1946 4 Sheets-Sheet s INVEN TOR.

" ATTORNEY I 4 Sheets-Sheet; 4-

IN VEN TOR.

- ATTORNEY ay wj p/ 7%. 797

wm wnmmm E. M. MAY

Aug. 19, 1952 HYDRAULIQ TRANSMITTER MECHANISM Filed Dec. 30. 1946 Patented Aug. 19, 1952 UNITED. STATES PATENT I F IcE HYD'RAULIC TRANSNIITTER MECHANISM V I Edward M. May, Detroit, Mich., assignor toMIeco- Pilot Manufacturing Company, a corporation of Michigan Detroit, Mich., f

Application December 30, 1946, Serial No. 719,305

The invention. relates tohydraulic transmitter means of hydraulic apparatus for the control and operation of machine tools and other powerdriven machines for which automatic control means isadvantageous.-. a

It is an objectof the invention to provide a compact and relatively simple automatic apparatus capable ofqcontrollingor directing the operation. of hydraulically driven machines.

A further object of the inventionis to provide such a'compact-control apparatus mounted independently. of the machine to be directed and adapted tobe moved and. positioned as a unit inrelation tothe directed machine, so that the directercan be .used atdifierent times to direct different machines and in use can be positioned to preserve free access to the directed machine.

The inventionhas as another, object the provision of hydraulic-pilot apparatus for directing positively and accurately limited power movements of a directed machine without the requirement of accurate correspondence between movementsof the. pilot apparatus and the corresponding movementsof the directed machine.

Another. objectof the invention is vto provide control apparatus having means affording continuous visual indication of the operation of the device so that departure from normal functioning or normal reserve of working'fiuid can be readily and quickly detected by an attendant.

A further object of the invention is to provide control apparatus of the character in question capable of varying its own speed and that of the machine controlled as may be desired throughout the cycleflof operations performed by the machine. v a

Other objects of the invention more or less incidental or ancillary to those already stated and various objects concerned with details of the invention will be apparent from the following description of an exemplary embodiment of the invention shown in the accompanying drawings.

For the attainment .of its various objects the invention consists in certain constructions, arrangements and combinations of parts hereinafter explained and definitely pointed out in the claims,

In the drawings, v

Fig. 1 is a front elevation of unitary apparatus comprising the main parts of the control means constituting the invention. I

Fig. 2 is a right side elevation of the apparatus shown in Fig. 1 with a" portion of the casing structure broken away to show interior parts and with hinged cover portions of the casing 11 Claims. (Cl. 605 4.6).-

drive of a turret lathe.

structure shown in closed'position by full lines andin open position by dashed lines.

Fig. 3 is a view partially diagrammatic showingone of the hydraulically actuated elements of a machine to be controlled, motor driven pump meansfor supplying power liquid for the hydraulic motors of the machine together with the principal parts of aunitary control mechanism in accordance 'with' the present invention, the'pa'rts of the control mechanism being shown in plan on an enlarged scale with some parts of the mechanism omitted and other parts shown in section to disclose interior construction.

Fig. i is an enlarged sectionalview on the broken line 4 4 of Fig. -3 withsome parts of the structure broken away. f

Fig. 5 is a section on the line 5 -5 'of Fig. 3.

Fig. 6 is a plan view, more or less diagrammatic, showing the invention as applied to the Fig. 7 is a diagrammatic view indicating the hydraulic transmittersot the control apparatus and a series of actuating'cams in developed form such as wouldbe appropriate in the use of the'invention for the control of the turret lathe. I

Fig. 8 is a face view of a cam blank useful in the design and fabrication of cams for the control apparatus.

The invention is particularly adapted for the control of machines or apparatus having elements or groups of elements operable by hydraulic motors, usually of the reciprocating piston type, and provided with some suitable source of working fluid under pressure, such as a motor driven pump which .may conveniently be associated with the machine.

With a machine, such as a machine tool, so equipped with hydraulic motors, the invention contemplates control apparatus comprising hydraulically actuated control valves of the follow type for the hydraulic motors of the machine and novel self-contained automatically actuated hydraulictransmitter apparatus adapted to be connected by conduits to the hydraulic actuating means of the follow valves of the machine motors and, byapplication of suitable hydraulic impulses to the. follow valves, to effect control of the machine operation.

Referring now in detail to the structures i1- lustrated in the drawings, numeral 1 designates as an entirety (Figs. 1 and 2) a cabinet designed to rest, upon the floor and house a hydraulic transmitterapparatuts' in accordance with the cabinet and at the same time serve as shelves for tools and parts when changes and adjustments of the apparatus are being made. The rear cover 4 is disposed at a higher level than the front cover 3 so that an inspection opening or window is provided at 5 forapurpose which.

will presently appear. The cover 4 is formed in its top portion with an opening 4b over which are arranged an electric light bulb 6, preferably of the elongated tubular type, and a reflector I, the purpose of the light being -to illuminate parts of the enclosed apparatus as viewed through opening '5. l H

Within the upper part of the cabinet I is a rectangular frame 8 secured to the walls of the cabinet by bolts or screws (not shown), the said frame being inclined downwardly from the rear to the front of the cabinet as shown in Fig. 2. As'bestshown in Fig. 3, the rear side of frame '8 carries a series of hydraulic transmitters 9, 9 two of'which; have been omitted to facilitate disclosure of other parts. Each transmitter comprises a block I9 formed at its front end with a transverse cylinder chamber ll (Fig. 4). This chamber is closed at its respective ends by heads 12 and I3. Within chamber H is a piston structure l4 comprising a disc 85, hydraulic packing-l 6 and retaining ring H. The piston is fast on a rod 18 which is guided at one end in a boss carried by the head [2 and at its other endextends through an aperture in the head !3 fitted with asuitable hydraulic packing [9. The cylinder block is formed on its top side with athreadedaperture 20 to which is connected, a conduit 2! designed to connect chamber II with receiver apparatus which will later be described.

The cylinder block IQ of each transmitter is also formed with a top recess to receive an upright, open-topped tubular reservoir 22 of transparent material such as plastic or glass. The reservoir is designed to hold oil or other working liquid for the transmitter and has its joint with block I0 packedto prevent leakage. Passages 23 and 24 lead from the bottom of the reservoir 22 into the cylinder chamber H, the passage 24 communicating with chamber II adjacent the closure head l3 while passage 23 communicateswith chamber H at a point intermediate passage 24 and passage 20. With this arrangernent the packing N5 of the piston structure serves to close the passage 23 as the piston moves forward on its working stroke. A coil spring 23 is interposed between the piston l4 and the head 12 and is adapted to retract the piston following its working stroke.

To effect the working stroke of the piston l4 cam devices are provided comprising a horizontal cylinder 26 having a cylindrical shell 21 and end discs 28, 28 which are centrally apertured and secured byset screws or the like on a supporting shaft 29. Shaft 29 in turn is supported by anti-friction bearings 30 in the respective ends of frame 8. To permit easy removal of the cylinder structure as a unit the end sections of frame 8 are fitted with swinging bearing caps 3% which are hinged at their front ends to the frame and are disengageably secured at their rear ends by swinging bolts 32.

The cylinder '26 is formed peripherally to receive a series of circumferentially extending cams 33, 33, one for each of the transmitters 9, 9. That is to say, thecylinderfhas a series of circumferentially extending cam seats 21a extending radially somewhat beyond the main surface of the shell 21, and adjacent each seat surface 21a the shell is formed with a circumferstraight longitudinal edge affording a reference surface to cooperate with the locating shoulder 2Tb. Each cam 33 is preferably formed from an elongated relatively thin strip of metal or other material susceptible of being manually bent from the flatstate to circular form and preferably also pcssessing suiiicient elasticity to return substantially ,tothe flat. state when released. Aluminum alloy sheetmaterlal of suitable temper is a satisfactory material for the purpose.

Each of the cams33 is. provided adjacent its two ends with apertures to receive securing screws 34, 34 which engage threaded holes 210, 210 of the f'cylinder drum 21, and is .also provided adjacent one end with a dowel hole to engage a dowel pin 35 attached to drum shell 2']. Each cam may if desired be provided with additional securing screws. spaced around the periphery of the cam drum... As will be apparent from Fig. 3, each ofthe cams 33 has one longitudinal edge formed with various lobes or active cam sections to effect desired movements of its hydraulic transmitter through the cam follower provided for that purpose. Such follower is in the form of a lever arm v36rfitted at its free endwith a roller 3] to engage the cam and pivotally supported at its other end in position to engage the projecting end of the piston rod l8. The pivotal support for the arm 35 is afforded by pin 38 car-. ried by the head of a bolt 39 having a. swiveling support in the rear part of receiver block It. With this construction the follower arm 36 can be raised when desired as indicated by dotted lines in Fig. 2 to permit removal of the cam cyl inder 26 from frame 8.v The swiveling bolt 39 is fitted with a washer 39a and a coil spring 40 which engages the .bolt washer and yieldingly presses the head of the bolt against the adjacent face of block I0 (Fig. 3). To support the roller 31 in operative engagement with the edge of the cam 33 the side of follower arm 36 where it engages the piston rod l8-is formed with an angular grooveor-depression 36a as shown, in Fig. 4. The engagement between the arm and the end of the rod is normally maintained by the tension of the spring 25. As is shown in Fig. 4 the follower :arm 35 during normal operation lies within aslot l3a of the cylinder head I 3. The purpose of this is to facilitate manual actuation of the cam follower for-certain purposes which will be referred to later in the description. The slot allows sufilcient lifting of arm 36 to disengage its roller 31 from the cam but maintains the arm in operative engagement with piston rod I8.

For reasons later explained it is desirable to be able to adjust the transmitter blocks 10 in relation to the supporting frame 8 and to this end each block is secured to the frame by a pivot pin 4| (Fig. 4) and a clamping screw 42 which passes through a hole in the block in somewhat larger than the shank of the screw so that the stopped by manual switch button 4%.

block ca be adjusted around the axis of pin 4|.

connected through worm and wheel gears to drive a pinion 46 meshing with a spur gear 41 fast on shaft 29 of the cam drum. -l referably the motor, variable speed mechanism and worm and wheel gears constitute a unitary devicewhich is supported on the end of cabinet I by a suitable bracket 48. With the described gear'connection between the motor and the cam'drum theremoval of the latter from its supporting frame involves merely-the disengagement of the bearing caps 3| and separation of s pur gear 41 from the driving pinion 46. For control of motor 43 it is connected in circuit with switch and relay devices 49 and 49', respectively, of well known construction, the switch having a starting button 49a and a stop button 49b. Further reference will be made to these manual control devices later in the description.

The apparatus is further provided with safety devices comprising an emergency switch 50 which is connected in circuit with motor 43. Switch 50 is normally held in its closed position by means of a double-ended dog 5l'fixedly secured to a rod 52 which is slidably mounted in bracket 53 and 54 attached to the frame 8 (Fig. 3). Dogs 55, 55 are adjustably clamped on rod 52, each a little to the right of the head of one of the pivot bolts 39. A coil spring 56 which is interposed between one of the dogs 55 and bracket 54 urges rod 52 toward the left. Rotation of the rod 52 is prevented by the disposition of the arms of dog 5| adjacent the horizontal surface of the bracket 53. With this arrangement if the discharge of any one of the transmitters should be blockaded or movement of the cam follower be in any way obstructed the spring 40 of the pivot bolt will yield and permit the follower arm 36 to swing about the end of piston rod 1 8 as a pivot with resultant movement of the sliding rod 52 toward the right and the opening of emergency switch 5|].

With the hydraulic transmitters actuated by the circular or endless form of cams it is apparent that a cycle of transmitter movements is eifected for each rotation of the camdru'm 26.- For the control of some types of machines and operations it may be desirable for the control mechanism, when started manually by switch button 49a, to run continuously for the performance of a considerable number of control cycles and then be In other cases; however, it may be desirable to "stop the control mechanism at the end of each cycle and have the apparatus started again manually. To

this latter end means are provided to open emergency switch 50 at the end of each rotation of the drum 26. Said means comprise a lever arm 51 fitted at its front end with an antifriction roller 58 arranged to be engaged by a radial pin 59 carried by cylinder 26. At its rearend the arm 5'! is slotted to receive the end ofeye bolt 6|! to which the arm is pivotally connected by to hold the arm 51 yieldingly against the side surface of block 62. The rear end of arm-5'! is engaged by the front end of dog 5| onthe sliding rod 52 and normally serves as {a positive stop limiting movement of rod 52 by spring 56. .With this construction when the control apparatus is started by actuation'o'f the starting switch 49d the cam drum 26 rotatesjin thedirection of-arrow R, until pin 59 engages roller-158m swing-the arm 51 around the'right front'cqrnerof block 62 as a pivot with resultant movementof th'e rear endof arm 51 to the right. This movement carries'dog 5| to the right and opensemergencyswitch 50 to stop the drive motor 43.1 Y

J In order to insure the 'properpositioning: of roller 58 inrelation to the'pinfor dog59, block '62 is adjustably secured toframe-8 by means of pin 65 and clamping screw 66; the'clamping screw having a suificiently loose fit'in-the block to permit the relatively small range of needed adjustment. When multiple cycle operation without manual control is desired it'is only necessary to I above described swinging movement of arm 51.

The purpose of switch 61 will appear at a later point in the description. I J H 1 It is desirable that the :stopping of the cam mechanism be eifected without any considerable overrun when the control switch is actuated. 'To this end the motor 43 is preferably'equipped with a magnetic brake so that :it will stoppromptly when deenergize'd I Alternatively (and at less cost) use may be made of. well known switch and relay circuit means adapted to give the desired quick'stopping. 1

The invention contemplates"automatic control I of the variable speed mechanism 44 through which motor 43 is connected to'drive the cam drum 26. To this end gearing44 is provided with a crank arm 4411 connected to actu'ate'the speed varyi g means of the mechanism.- As has been stated any suitable form of'spe'ed'varyingmechanism can be employed 'b'utthat manufactured by Graham Transmissions Inc. of' Milwaukee, Wisconsin, and shown in U; S. =Patent :No. 2,405,957, has been found satisfactoryiforause.

Crank arm 44a is actuated bya hydraulic receiver comprising cylinder Bil-and?pistonliflhaving a rod 10 with a pin and slotoo'nnection to arm 44a. One end of cylinder 68 isizconnected by a conduit 2| with one of the hydraulicg'transmitters 9. Thus the hydraulic impulse of the. transmitter serves to move the pisto (i9 against the tension of a retracting spring 1| interposed between the piston and one end of cylinder 68, The speed change mechanism and the connections between it and arm 44a are such that the piston move-' ment opposed to spring-1| increases the speed transmitted through pinion 46 and gear 41 to the cam drum. Movement of piston 69 in the reverse direction by spring 1| correspondingly reduces the speed transmitted .to :the camvcylinder. To determine the maximum and mi'nirnum speeds which may be thus automatically provided bythe hydraulic mechanism adjustable screws 12,- 72 are mounted on bracket .IS Icarried by the'casing of mechanism 4.4 and. serve t 'lmt' the swinging movement of lever 44a. H I H By means of the describedlh V aulicf devices for determining thespeed 'ofjr'otationof the cam drum 26 it is possible by the provision of a suitably shaped 4 cam for] actiijating the transmitter connected to cylinder '68to vary thesp'eedf of cam movement at will throughout the cyclof rotationofthecamdrum; Y

In Fig. '3'of'the'dra'wings1s shown more or 1ess amt- 2 diagrammatically a :machine element, hydraulic rmotoridevicesxandipressure fluid .supply means for themotor device connectedini a typical man- ;ner to thes'hydraulic transmitter control mechanismalreadydescribed. The machine element 14 maybe taken as (a portion of-the turret slide of the turret lathelshown in Fig. 6. Associated with the slide is a hydraulic motor-comprising a cylinder ldanchoredat l6 and having a piston 11 with rod reconnected by arm 19 to the slide element 14. This hydraulic motor is fitted-with ahydraulicallyactuated control valve'of the follow type. The valve comprises a casing 88 providing a chamber 189a fora spool valve 8! and a chamber-80b foran actuating piston .82 having its rod 83'extending intochamber 80a to urge the valve 8l toward theccight against the tension of :spring 84. .The chamber 80b is connected on the leftside of piston' 82 with one of-the conduits 21 leading to one org-the hydraulic transmitters 9.

Pistonrod 18 of =the-main motor carries an arm 85 to .whichis attached a follow rod 86 extending into chambjer'ilflb. The latter chamber, onthe branches to .supplya plurality of hydraulic motors.- 1 One such branch 92a isshown connected to the inlet port of valve casing 88. The right end of the control valve chamber 89a discharges to a return pipe 93delivering-into sump 9U. *Pipe .93 may also have branch return lines leading into 'it as indicated in Fig. 3.

To control the pressureof the working fluid deliveredto thehydraulic motor or -motors served by it discharge :pipe .92 is fitted with a by-pass valve "94 of "well .known construction which is equipped with relied valvedevices comprising casing -95,.ball valve 9.6 and .coil spring 9'! which yieldingly'urges the valve against the inlet .port of casing 95, 'th'e outlet'port being connected by 'conduit 98 to'su'mp 90. 'Toautomatically vary the tensionof spring:9l:casing 95 is provided with a chamber 99 forhydraulic piston 100 having a rod IBI engaging the endiofspring .91. With chamber 99 connected as shown through a conduit 2| with one of the hydraulic transmitters 9 the impulse of thetra'nsmittendetermined by its a'ctuating cam, serves to vary the tension of spring 91 and hence'the pressure at which the valve '96 opens to control the'openingof by-pass valve 94.

Casing struc'ture95 is provided witha relief port IDZ on the right side of piston! DB.

From what has "been 'said'it is apparent that the control apparatusis adapt-ed automatically to control the amounts or distances of'the powerdriven movements of one or more machine elements, to control the pressure of the working liquid supplied'to the motor or motors of the machine elements ,during or'in different parts of the movements of the said elements to thereby vary the force of theindividual movements, to control the sequencein which the movements of the machine elements occiirand also to control the speed with which-thercycleor. cycles .of machine element movements, .orlparts'fof such cycles, are

.carried out.

To further illustrate the-mannerof applying devices .15", '80.

:8 Fig. :6 shows in plan view the application of the invention .to :a turretllathe. The .figurelshows the already described cabinet l with its variable speed motor :drive mechanism and its series of hydraulic transmitter conduits 2i, .2! and also shows the already described motor pumpmechanism for supplying liquid under pressure to hydraulicmotors to-be automatically controlled together withgthe turret lathe designated as van entirety by the numeral I93. Thelathe hasa frame structure 104 upon which the slidell-carrying turret mechanism 105 is slidably-mounted. Slide structure I4 is fitted with th motor and valve mechanism '15, Bil-already described in connection with Fig. 3. A collet chuck -meehanism ltlifor,gripping and advancing the workto the tools is similarly fitted with motor and;contr0l valve-means .15, flfl and across slide mechanism I01; is similarly fittedwith motor andcontrol valve The 'turret, :collet and .oross slidedevices arefitted withthe usual limit stops (not shown) to positively limittheir respective feed and retraction movements. The transmitter conduits 2 I of the control apparatus are shown connected to-the speed control and pressure control-devicest landrfli and to eacher the hydraulic motor'devices, although theconduitsto serve the motors of thecolletand cross slide mechanism areipartlyt broken away to avoid undu complications." 1

:It will be observed that the cabinet-encased director iscOnVeniently disposed infront of the lathe but spaced from it to provide passageway between the twodevices andsecurefree accessto bother them. The transmitter conduitsll are convenientlydisposed ati'floor level betweenthe twomachines and covered and protected by a floor plate H38.

By way-of further'explanation of thezinvention there ;.is :shown in Fig; 7 of the drawing an exemplary set of actuating camssuitableifor controlling the operation of the turretlathe shown 'inFigQS. ,For clarity the cams are shown in their fiatform detachedfrom'the supporting cam cylinder. From top to bottom of the figure the cams are designated cross slide, collet (for feed of work piece), turret, pressure and speed, corresponding to the several control stations which have already heenreferredto in the preceding description. Fig. 7 also indicates in connection with each cam the follower arm 3t and transmitter El driven by it.

It is observed first that each of the cams 3.3 is marked with a longitudinally extending base line H19 which is spaced exactly ata standard distance from the reference edge of the cam and the surface of the cam at one sideof this line is marked with transverse lines H0 dividing the length of the cam into equal subdivisions (Fig. 8), every tenth subdivision being numbered from the starting end of the cam upward. The cams move in direction of .arrow B. To facilitate the design and fabrication of the :cams, blanks HI areprovided as shown in Fig. 8. The width of thesubdivided zone of the blank atone side of the bas line is such as to provide for the maximum rise of the cam correspondin to the maximum working stroke of the transmitters 9 of the apparatus. Since the length of the cam measured along the base line represents time in the rotation of the cam cylinder and transverse distances measured from the base line represent movement of the transmitter mechanism (and therefore of the receivermechanism'actuated by the. transmitter) it will be seen that a cam havs. atmis11t lin sl eepre n a sub entially uniform rate of ;transmitte r displacement f siv n s ed of ca t t on The y:

strai ht line slopes, where the outline may be rounded somewhat to avoid vthe shock of too abruptchange. Thus a cam in accordancewith the present invention has a cam surface made up essentially of a connected series ofplanar surfaces that can readily beiformed with a high degree of accuracy.

From an inspection of Fig; 7 it will be seen that each of thecams .has. its active edgeon orabove the base line I09. except. that. at one point, in the case of .each-cam, a notch.ll2 is formed to permit the cam follower to move below the .base line..The purpose of the notches 1 I2 will be explained presently in tracing the operation of, the apparatus. V H v Operation I Assuming that the ,controlapparatus which has been described provided with a set of cams suchasarc hown inFig. 7 and the apparatus is to be connected as shown inFig. 6 tor the control of theturret lathe, in anqinitial use of the apparatus it would be appropriate to fill with working liquid the transmitter and receiver chambersvand the conduits 2| connecting them. To facilitate, the introduction of the working fluid thereceiver part of the control valve casings 80 may be provided with air vent apertures normally closedby screwplugs such as shown at 80c (Fig. 3). Having removed orloosenedplugs 800 the working liquid, which will preferably be colored redor 'some other strikingcolorthat will readily catch the eye, may be introduced into the open topped reservoirs 22 of the several receivers. Withthe transmitter pistons in their right hand positions and with theclosure plugs 800 open to permites or air, the; liquid willflow from the reservoirs through passa e 23-into the transmitter chambers and thence through conduits 2! to theseveral-receiver chambers, whereupon plugs 80c may be replaced or retightened. During the I filling operations thecam follower arms 36 may be moved manually to actuate transmitter pistons M for the purpose of facilitating the filling of the conduits 2| and receiver chambers. The.

fact that conduits 2| are made of transparent material permits the detection of any air bubbles in the line, and upondiscovery of suchbubbles the nearest-joint may be opened or loosenedsufi'zlciently to permit the trapped air to be vented to the atmosphere. H v

With the control system suitably filled with working fluid the next step. in initiating operation of the apparatus is adjustment ofthe blocks 10 of the transmitters 9 to insure the proper positioning of the transmitter pistons 14 in relation to the passage 23 when thecam follower roller is tangentto'the base line ofthe cams. Such adjustment can conveniently be made before cams are attached to the supporting cylinder 26 by on the: cylinder in place of the cam a short gauge having a width equal to the distance the levelof the liquid starts to fall incident to 10* between the base line of a earn and the right edge thereof as viewed injFig. t such gauge being moved from one cam seat toanother as the blocks I0 are successively adjusted. Ineffecting the adjustment the anti-friction roller of arm 36 is held against the edge of thegauge, and with the clamping screw 42 loosened, block I0 is turned in the clockwise direction on pivot pin it to permit spring 25 tomove the-piston to the right of pa ssage 23 The bloick It thenslowly turned the opposite direction to efifect movement of piston I d toward the left (Fig 4:). During this movement the level of the liquid in reservoir 22 remains fixed until the front edge of piston packing l6 completely closes passage 23, at which point flow through passage24 into the space to the right of the piston. Thestart-ojf the change in the liquid level thus indicates the point at which the clamping screw d 2; is to be tightened to fix the block NJ in its proper working position. in this connection it will be apparent that the supporting bearings of the cam cylinder must be such as to avoid endwisemovement of the cylinder. I

With the adjustment effected in the manner stated the cam cylinder may be lifted from its bearing supports for the mounting thereon of cams suitable for the particular motor-driven machine or operation to be controlled. For the control of the turret lathe (Fig. 6) it may be assumed that the set of cams shown in Fig. 7 is employed. If the machine is to be stopped automatically at the end ofeach cycle the control arm 51 willbe lowered into operative position to be engaged by dog 59 of the cam cylinder. The operator or attendant starts the operation by pressing button 49a. of switch; 49, The cam cylinder thereupon is rotated in the direction of arrow R (Fig. 3) to carry out the cycle of operations determinedby the forms of the f ve cams.

As illustrative both of the kinds of considerations involved in the design of the cams and of the advantages attained with the present invention some of the characteristics of the cams of Fig. 7 are here noted. In the case of the turret cam there is a level-topped lobe between 0 and 19. This results in turretstation I- (Fig. 6) being held toward the left with the turret stop rod presented to the bar stock coming throughthe spindle. Correspondingly the collet cam has a rise andfall between 0 and 10, whichcauses the collet mechanism first to open and retractand then-close and advance bar stock through the spindle. This requiresheavy hydraulic pressure for cylinder 15' which is provided forby making the pressure cam with a high lobebetween 0 andlO so that the pump 88 will provide its maximum pressure. It is desirable to operate thecollet rapidly but the cam slope that can-be used is limited to about 45 to prevent undue tangential stress. Consequently it is desirable to turn the cam drum rapidly and the speed cam is made high to provide the high speed; Meanwhile the cross slide cam is level at onlyz half the maximum height to hold the cross slide in central or inoperative it on- 'i r s- 1 At point It the turret cam drops, (rapidly at first but more slowly at the end where the cam slope is curved) to retract the turret and index it to its number 2 pos ition whereupon it is again returned to the work. As will be noted,;the form of the cam for this return motion, is first fast and then slower atfeedrateas thedrill engages the work, the flatter cam slope at' 20 being for aged-7,196

the feed motion. This operationtakes-some-time andthe-drumshould-continue to-turn at high speed an undue portion of the drum circumference wouldbeexhausted. Accordingly the speed canr is made low beginningat' about 17.

Nextthere-follows a falland rise of the turret cam-between 24; and-30-which indexesthe turret to its number 3-position; Such indexingcalls for a long rapid stroke-sea corresponding rise be-- tween" 24-- and 30'is provided on the-speed cam.- Similarly-turrettools 3- and- 4' are fedthrough to 50 on theturretcam and thenfollows-two-indexes for the emptyturret stations 5 and 6 to point i3-oirthe-camz Just as thelast turret tool is retreating a t-'48 (turret cam), the cross slide advances to-present thefront-forming tool; This is along feed movement but there is plenty of can length available tofinish the operationso the moderate rotationalspeed is maintained as shown by'thelevel-section of'the speedcam from 44 to 85. After the-front forming cut is-finished by the cross slide; itscam' reverses at Ti and, between75and'85; presents-the rear cut-ofi tool to'cut-off the-work-piece At some point in each rotation of the cam drumit is-desirable to effectrefillingof-the hydraulic pilot systems and in-the case of the turret lathe applicationitis convenient to provide each cam witha filler notch-H 2- between points 85' and- 99 on the several cams. These notches fall-below the base line I09 of thecams and; as will be-recalled, this permits thefront edge of packing it of piston 14 (Fig. 4') topassto the right of passage 23-thus opening chamber I Ito-reservoir 22. This allows replenishment to compensate for anyslight leakage and to permit escape of air upward through the reservoir; Theappearanceof air bubbles rising in-the reservoir will warn of a leak somewhere in the pilot system andthe operator can promptlylocate the leak and-remove-it.

Thus the pilot systems are normalized once in each cycle; In thepresent example this action occurs at the same time-in-allof the pilot systems but the filler notches of the-cams can be located at any point that does not interfere with an active operation;

Between-points 90 and lflflall the cams return to-their original heights tomatchthe zero ends ordinate graphs of the operations to be performed 7 and can be laid out by any-intelligent mechanic havinga-knowledge of the machine operations to be controlled. Furthermore the cams are'light in weight and when dismounted from the drums take substantially theiroriginal flat form which facilitates their compact storage for use at a future date. They form and preserve a record of timing andfeed rates" that in other types-of apparatus would have to be worked out anew'with each repeated setup; This is unnecessary with the improvedcam apparatus because of the mannor in which thecams are laid out and-positioned The dismounting of a set of cams from the carrier or their reassembly thereon is facilitated by theeasewith which the carrier can belifted from its bearing supports and' moved to similar supports at a workbench; This also ha's theadvantage that anymechanism of whiclrthecam apparatus a part is-not tied-up while the-cam set-up is being changed.-

The possibility oflaying out-and mac-hiningthe straight line can surfaces on flat strip materiai enormouslysimplifies and facilitates the -fabri'cation, in comparison with-prior practice; Thus thefiat cam-strip can be gripped in-a fixture for grinding on a surface grinder and a required planar camsurface produced with 'ahigh degree of accuracy a very short time; and with -all=of the cam surfaces of a cam strip: laid out -and ground with reference to the commonreferenceedge-of the strip a-cam can-be completed'ina. much shorter time and at a-much-lower cost than-- isfeasible by other known methods of cam fabri cation of comparable accuracy;

Design considerations the springs (Fig; 3) associatediwith-the pivot bolts 39 should be of; a length; to permit sufiicientl movement of the bolts .to; accommodate theifulla throw of the actuating cams so thatlifvffor'anyi reason the safety switch 50 shouldifail tooperate; no harm will be done. The springs 40 should be stronger than the retraction springs 25 of the transmittersand spring in the-fol1ow valve -flfl so asnot to yield under maximum normal pressure inthe pilot system: Thespring-EG associated with safety rod 52- should; of course, be strong? enough to overcome friction'of the rod 52 in its supports-and closeswitch 50.

Spring 25 of the transmitters-need not be-a heavyone but is" needed toretract piston Win case leakage from the system results in insuiifrcientlworking fluid for spring 84' of theifollowvalve to return piston-pacliing lG of the' t-rans mitter iar enough to uncover replenishment pas' sage 23. In case of such 'fluid'shortage apartiab vacuum will be formed by the retraction -of piston- M byspring 25 with'resultant collapseof pack ing Hi from the wall of chamber H and a'dini'ssion of working fluid to 'said'chambe'r from the reservoir at any part of thereturn stroke:

The hydraulic pilot system comprising trans== mitter chamber 1 l; conduit-2 1andreceiver'cham ber 8012 constitutestheoreticallyarigid meansoi" transmitting motion fron'r cam 33 to piston 82 of the receiver; Practicallythis ideal is not realized; Camfollowe'r arm 36 w-ill flex slightly, under load, the" various hydraulic packings are" resilient and slightly-compressible and there is? usually aslight amount of compressible airinf the working fluid. Therefore'for'uniformity of action it is important toj-keentheload on the pilot system as nearly-constant as -possible: this load islargely determined byspring 84 of the control valve spring-'- should"- be made sufficiently flexible so that" it does-'- not change 13' and cross slides and the collet of the turret lathe. The controls of the cam speed and of the work,- ing pressure of the power liquid do not call for high accuracy either as to amount or timing.

In applying the present invention to the control. of such definitely limited machine movements the yieldable mounting of the cam follower arms makes it possible to design the pilot cams to produce slightly longer transmitter strokes than are required to complete the power driven machine element movements to engagement with their respective stops; for when engagement with the stops occurs the small additionalmovements of the cam followers are accommodated by the yielding of springs 40.- It is to permit such small movement of pivot bolts 39 without opening switch 50 that small clearances are provided between bolts 39 and dogs 55 (Fig. 3).

The control valve 8| can be made practically non-reactive to liquid flow through it. Rod 83 enters the power system on the exhaust side where the pressure is nominally zero. In practice this pressure varies widely and may rise to quite a high value. Rod 83 should therefore be made as small in diameter as is mechanically practical to minimize the effect of exhaust pressure variation. .An adequate vent passage 8! is required to positively protect the pilot system from gaining oil from the power system.

In the design of the follow device for the motor control valve it should be observed that the movement of the motor piston 11 is determined by the cubic displacement of transmitter piston II in relation to the cubic displacement of the follow rod 86 of the hydraulic receiver. Thus if it is desired to provide a motor cylinder 15 with a longer stroke, rod 86 must be lengthened but correspondingly reduced in diameter. In a word the hydraulic motor with its hydraulically actuated follow valve constitutes a hydraulic power amplifier of known character.

In connection with the device for controlling the pressure of the power fluid, it might seem that the desired control is a mere matter of transmitting suitable pressure to the relief ball 96 (Fig. 3) and that resilience in the associated pilot system which applies the pressure would not be detrimental. However, it has been found necessary to make the pilot system as little reactive to exhaust pressure as possible. Accordingly the piston rod lDl which engages the spring 91 is made of small diameter relative to piston I00. If this is-not done the device chatters badly.

In actuating machines by hydraulic pressure it is generally desirable to employ pressures only moderately higher than is necessary to do the required work. In the present improved apparatus the provision for the automatic variation of the pressure of the working fluid supplied to the power motors meets this requirement of moderate pressures.- However, possible abnormal variation of operating conditions renders such provision of automatic control insufiicient. Thus in the case of control of machine tools if a cutter developed marked dullness or if a slide were blockaded accidentally the actuating motor cylinder would be unable to follow the impulse of the pilot system and, as appears from Fig. 3, the follow rod 86 would not withdraw from the chamber 80a as fast as liquid was delivered from transmitter 9. Under these conditions it is apparent that the liquid in the pilot system would be blockaded and piston M of the transmitter would not respond to its actuating cam. In such a case spring 84 of the follow valve, depending on the position of the latter,

might yield'somewhat and'afiord some relief, but I for general reliance it is, clear that the yieldable mounting of the cam follower arm 36 and the safety switch provision of the directer apparatus are needed.

While the inventionv has been shown as em bodied in a unitary cabinet disposable apart from the machine to be controlled, it will be understood that in cases where machines to be controlled (for example, special purpose machines), are intended to be operated continuously the cam-driven transmitter mechanism can be mounted on the frame of the controlled'machine and that the compact unitary character of the mechanism, comprising the rotary .cam drum, the hydraulic transmitters and the common supporting frame of thoseparts, especially adapts the invention to such applications.m-

When the directer is operated in a manner previously described to stop the cam cylinder automatically at the end of each cycle, the directer can be re-started only by pressing the start button of the manual switch 49. For this reason it may be desirable in many instances to mount the stop and start switch on the directed machine and connect back to the directer with suitable wiring.

In the illustrative embodiment of the invention disclosed .herein theinvention' is applied to the direction of a power driven machine having movements of its elements accurately determined in amount by fixed stops forming parts of the machine, but it .is to be understood that fundamental principles of the invention are applicable also to the direction ofother types of machines in which it is not feasible, or not desirable, to make such use of fixed stops. An example of such other machines is found in duplicator machines in which the work-engaging tool travels in an irregular path determined by a model of the thing to be reproduced.

To those skilled in the relevant arts it will be apparent that the present inventionis applicable to the control of a wide variety of machines and that the manner of application and the structural embodiment of the invention both as a whole and in its parts may take. a wide range of equivalent forms within the bounds of the following claims.

What is claimed is:

1. In hydraulic apparatus, the combinationof a plurality of fluid pressure transmitters of which each comprises a cylinder and a cooperating piston; cam means for actuating the transmitter pistons comprising a movably mounted cam carrier, cams mounted thereon and driving connections between each cam and one of the said transmitter pistons; variable-speed motor means for actuating the oam carrier; and hydraulic means actuated by one of the transmitters for control-' ling the speed of the motor means and thereby of all the cams. a

2. In a hydraulic apparatus, the combination of a plurality of transmitters each comprising a cylinder and a piston," cam means for actuating the transmitter pistons comprising a rotatably mounted motor-driven drum, cams mounted on the drum, cam followers, and yieldabl'y mounted supports to which-thecam followers are pivotally connected; means for controlling application of the motor power to the drum comprising a movably mounted device common to the yieldable supports of the cam followers and operable by yielding movement of any one of the said supports to interrupt the application of power to the drum.

3. Apparatus as claimed in claim 2 in which the movably mounted device common to the yieldable s eam-rest supports of the cam followerszis operable: byrsaid: supports. :only after a predetermined yielding movement of thezlatter... Q

4; In hydraulic apparatus, the combination-of a plurality of transmitters each comprising a cylinder and; a piston cam .meansifor: actuating the. transmitterpistonscomprising a rotatably mounted drum,.:eams mounted; on the drum, cam followers, and: yieldablyamounted supportsto which the cam .followerszare pivotally "connected; electric motormeans. forlr'otating the cam: drum;

a switchlior. controlling: the. motor circuit;. and

movably mounted meanszcommonto the yieldable supportsiofi the cam: followers and operable by yieldingrmovement:otanymnei of said supports.

to openathe. motor circuitiswitchi 5. Hydraulic apparatusasiclaimed in c1aim.4

in which the means for opening the motor circuit switclris operable .bytheyieldable supports of-the camfollowers.onlyiafterv aipredetermined yielding.

movementof'asupport... v

6. In. hydraulic apparatus; the; combination of hydraulic. transmitter. means comprising; a.cy1in-.- der,. aL-piston. therein and; cam means. for. moving the. piston; apart of. the. transmitter means being adjustablarelative to the: cam meanswhile: the

transmitter. means 7. are .operatively. assembled; a reservoir for working: fluid associated. with. the transmitter. cylinder means .affording communi-.=

cation. between the;.reservoir.- and .the working;

the. piston,. the point at .whiclr communication between: the: reservoir and the. working space of the. transmitter cylinderon .the advance side of the piston iscut oft inthe advance movement; of

the transmitter piston being variableinrelation to the movement of; the. cam. by; adjustment: of the adjustablezpartiottheisaid; transmittezzmeans and movement ofzthe level of .fluidiin the reservoir serving: during such; adjustment; to. indicate; the

cut-off;positiomoithepistom.

7-. Hydraulic apparatus as ;claimed: inzclaim: 6 in which the'transmittermeanscomprises a plurality of sets of cylinders, pist'onsand; reservoirs and.the cam means comprises a: plurality. of. the cams mounted. on; a; common movable support, with each. cam cooperatingwith one of. the said sets;

8; Hydraulic apparatuses claimedin claim 6 in which the transmittercylinder constitutes the adjustablepart of the transmitter means.

9; In hydraulic apparatus, the combination of hydraulic transmitter meanscomprising a cylinder, a piston therein and meansfor advancing andretracting the piston; an upright open-topped reservoir for working fluid disposed, at; alevel abovethe cylinder, said reservoir having;a1transparent wa1l,-a uniform-boreanda volume'not less than the maximum workingdisplacement of the.

the fallandriseot liquid inlthe reservoir during theadvance andretraction, respectively, of the pistonr lfllrInihydraulie apparatus; the combinationtof:

hydraulic; transmitteri means: comprising; a cylinjder; a. piston therein" and: means for; advancing and" retracting the piston; ,an upright-open-topped reservoir for: working fluid disposed at, alevel above, the cylinder; saidgreservoir having a transparentzwalLa uniform bore and-a volume not less than: the: maximumworking. displacement of the piston; means affording. communication between thereservoir'and the workingv space of the transmitter cylinderon theadvance side of its piston only whenthe said; piston is in retracted position;

and means affording, substantially continuous.

communication between the reservoir andthe transmitter cylinder at the, rear of its piston, whereby; movement and position of saidpiston is shown bythe fall and-rise, of liquid in the reservoir during the: advance and retraction, respectively, of the piston;

11; In hydraulic apparatusrthe combination of a: cylinder; and piston. transmitter; a: cam drum rotatably-mounted adjacent to the transmitter; a cam ex-tending around thedrum and supported thereby,-.said cam having azcam surface disposed transversely of'the drumaxis; and drive'means between-the cam and {the transmitter piston comprising a lever arranged to-engagethe said cam surface as follower and pivotally mounted to permit its disengagement from the cam bygmovement transverse; to the drum-axis without its" operative disconnection from the transmitter piston-whereby the lever'can be manually disengaged ,from'the cam and-moved manually to actuate'the transmitter:

EDWARD M. MAY.

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